Atom transport and the change in surface composition during ion implantation in multicomponent materials

A nonstationary system of equations describing the dynamics of the component concentration distributions in a multicomponent material, taking into account implantation, sputtering, external deposition, and diffusion, is obtained. The boundary conditions are formulated. Approximate solutions that make it possible to analyze the effect of different factors on the formation of the concentration in the layers near the surface are given. Zh. Tekh. Fiz. 67, 95–99 (October 1997)     

New allotropic form of silicon

A new allotropic form of amorphous silicon with sp hybridization of the valence electrons is discovered. The new material consists of linear chains of atoms. A small fraction of the atoms are in the sp ² state. Acting as bridges, these atoms couple the linear chains into a single random network. This conclusion is based on an analysis of experimental data on the effect of annealing and ion implantation on the structure of the short-range order and the properties of amorphous-silicon films obtained by different methods. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 9, 646–649 (10 May 1998)     

Modeling of a method of freezing a metal coating onto optical fibers

A model is developed for a specific technological process used to deposit metal coatings onto quartz optical fibers, which are finding increasingly widespread applications. Zh. Tekh. Fiz. 67, 100–109 (January 1997)     

On the experimental possibilities of observing single spins in a STM

A method is proposed for observing the spins of individual particles by combining ESR and STM methods using a ferromagnetic needle or paramagnetic tip. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 7, 484–488 (10 April 1998)     

Expansion of an arbitrary function in products of spherical functions

A formula for expanding an arbitrary function defined in the interval (0,1) into a series in products of spherical Legendre functions of the first and second kinds is presented. Examples of expansions of this type are given. Zh. Tekh. Fiz. 67, 123–126 (June 1997)     

Hamiltonian dynamics of vortex lines in hydrodynamic-type systems

It is shown that the degeneracy of the noncanonical Poisson bracket operating on the space of solenoidal vector fields that arises due to the freezing-in of the curl of the velocity [E. A. Kuznetsov and A. V. Mikhailov, Phys. Lett. A 77, 37 (1980)] is lifted when the vorticity Ω is represented in terms of vortex lines. This representation makes it possible to integrate the equation of motion of the vorticity for a system with the Hamiltonian H=∫∣Ω∣d r. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 12, 1015–1020 (25 June 1998)     

Electron g factor in quantum wires and quantum dots

A theory of the Zeeman effect for electrons in one-and zero-dimensional semiconductor heterostructures is developed. A relation is established between the number of linearly independent components of the g-factor tensor and the point symmetry of a low-dimensional system. A specific calculation is performed for a spherical quantum dot and a cylindrical wire. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 1, 41–45 (10 January 1998)     

Peculiarities of heavy ion channeling

Abstract

Depth distributions of implanted Mg⁺- and Ca⁺-ions and the corresponding radiation damage were studied for different channeling orientations of silicon crystals. The shape of the implantation profiles is discussed by using simple models for dechanneling and energy loss processes. A correlation between dechanneling, damage production and depth distributions of the channeled ions could be observed. This correlation is seen by the maxima shifts in damage and implanted ion distributions between channel and random incidence.     

Growth of periodic Hg1−x MnxTe structures by liquid-phase epitaxy

A procedure for the calculation of phase equilibria in the tellurium corner of the phase diagram of the ternary system Mn-Hg-Te is described within the framework of the model of regular associated solutions. The initial concentrations of the nonstoichiometric fluxed melts and the temperature regimes of their cooling for the controlled liquid-phase epitaxial growth of inhomogeneous Hg_1−x Mn_xTe structures with prescribed modulation of the composition along their thickness are determined by numerical solution of a nonlinear inverse Stefan problem. Zh. Tekh. Fiz. 67, 64–67 (September 1997)     

Recovering the spectral profile without measuring the instrument function of the analyzer

A method of recovering the spectral profile without measuring the instrument function of the analyzer is considered. Conditions for the existence of a solution for this method are determined. A numerical test of this method for the Auger spectra of silver revealed that it was highly effective at noise levels up to 1% of the amplitude of the line. Zh. Tekh. Fiz. 67, 110–113 (January 1997)     

Device for measuring the parameters of an ion beam of circular cross section, permitting estimation of the beam emittance per pulse

A diagnostic device is described for estimating the beam emittance per pulse (for pulse durations from 1 ms up to a continuous beam) for ion beams of circular cross section with currents from a few milliamperes to hundreds of milliamperes and energies of 10 keV and higher. Zh. Tekh. Fiz. 67, 135–136 (September 1997)     

Sufficient conditions for the existence of Q balls in gauge theories

A set of simple sufficient conditions for the existence of Q balls in gauge theories is formulated. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 4, 229–232 (25 February 1998) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Calculation of the ranges of slow, heavy ions in an amorphous medium

The low-energy range corresponding to reduced energies ɛ⩽0.1 is investigated. A method is developed for calculating the ranges of heavy ions in an amorphous medium. Analytical expressions for calculating the projective range of ions and the standard deviation of the projective ranges are obtained. The computational results are in good agreement with experiment. Zh. Tekh. Fiz. 67, 16–20 (October 1997)     

Magneto-optical and magnetic properties of (YBiSmTm)3(FeGa)5O12 ion-implanted films

A strong dependence of the meridional Kerr effect on the implantation regime that is different in different segments of the spectrum has been observed in He⁺-implanted (YBiSmTm)₃(FeGa)₅O₁₂ films. In addition to the Kerr effect, we have also investigated the dependence of the magnetization, the magnetic anisotropy, and the Néel temperature on the conditions of implantation. Correlations were noted in the behavior of the magnetic, magneto-optical, and electrical properties of the implanted layers. Fiz. Tverd. Tela (St. Petersburg) 39, 1267–1269 (July 1997)     

Parametric excitation of oscillations of charged particle bunches in a Penning trap

A self-similar solution is obtained for the self-consistent hydrodynamic equations describing the motion of an ellipsoid of charged particles in a Penning trap and in an rf trap. The conditions are determined for which a small periodic variation of the confining magnetic field in the Penning trap drives oscillations of the bunch. Zh. Tekh. Fiz. 67, 27–29 (January 1997)     

Calculation of the force characteristics of a multi-coil suspension of a superconducting sphere

The theory presented in the accompanying paper [Ref. 1: Zh. Tekh. Fiz. 67(1), 3 (1997); Tech. Phys. 42, 1 (1997)] for the calculation of the magnetic field and the force characteristics of an electromagnetic suspension for a superconducting body is used to carry out specific calculations of the force characteristics of a multi-coil suspension of a superconducting sphere. Formulas are obtained for the dependence of the force and the stiffness, from which it is possible to approach the problem of the stable suspension of a superconducting sphere in the field of a system of circular currents. The problem of determining the magnetic field at the sphere is analyzed and the conditions are found for which it is less than the critical field. Zh. Tekh. Fiz. 67, 10–16 (January 1997)     

Ultrasonic monitoring of the accumulation of aging damage and recovery of the useful lifetime of industrial parts

A method is described for monitoring changes in the strength properties of steels during fatigue testing based on measuring the velocity of propagation of ultrasound. It is shown to be possible to detect the dangerous stage of development of fatigue damage for individual industrial parts. A method is also proposed for restoring the function of manufactured items by treating them with high-power electric current pulses. It is shown that such treatment significantly increases the useful lifetime and can prevent fatigue failure. Zh. Tekh. Fiz. 67, 123–125 (September 1997)     

Calculation of the interaction force between a relativistic electron beam and an Ohmic plasma channel

A formula for calculating the interaction force between a relativistic electron beam and a preformed Ohmic plasma channel with an arbitrary offset of the channel axis from the beam axis is obtained in the case of complete charge neutralization. It is shown that this force is repulsive for radial profiles of the conductivity with a peak on the channel axis. Zh. Tekh. Fiz. 67, 69–76 (June 1997)     

X-ray diffraction studies of silicon implanted with high-energy erbium ions

Silicon crystals after implantation of erbium ions with energies in the range 0.8–2.0 MeV and doses in the range 1×10¹²–1×10¹⁴ cm⁻² have been studied by two-and three-crystal x-ray diffraction. Three types of two-crystal reflection curves are observed. They correspond to different structural states of the implanted layers. At moderate doses (1×10¹²–1×10¹³ cm⁻²) a positive strain is observed, due to the formation of secondary radiation defects of interstitial type. An increase of the implantation dose is accompanied by the formation of an amorphous layer separating the bulk layer and a thin monocrystalline surface layer. At an implantation dose of 1×10¹⁴ cm⁻² the monocrystalline surface layer is completely amorphized. Parameters of the implantation layers are determined. A model of the transformation of structural damage is discussed. Fiz. Tverd. Tela (St. Petersburg) 39, 853–857 (May 1997)     

Numerical simulation of achromatic deflecting systems

A deflecting system formed by two parallel-plate capacitors on opposite sides of an optoelectronic element that alters the energy of a beam of charged particles, is calculated numerically. The conditions for correcting the chromatic beam spreading in the plane of the target are found. Good agreement with the results of an approximate analytical calculation is demonstrated. Zh. Tekh. Fiz. 67, 86–88 (December 1997)